The invention relates to a system of machining devices particularly for machining so-called lead frames, such as punching, cutting and bending. Such lead frames are intended for carrying chips. The intended processes to be performed on the lead frames are performed in a so-called cutting and bending machine. Such a cutting and bending machine needs to combine great accuracy with the highest possible machining speed. For machining the lead frames are carried by means of transporting means through the machine, placed on a machining station and subjected to a machining, whereafter the transporting means pick up the lead frames again and transport them to a following station. The entire process takes place automatically.
In older machines the machine tool is driven via pneumatic means in order to perform an active stroke. A pneumatic cylinder coupled to the tool carrier is employed for this purpose. Later machines were driven via hydraulic means since the forces generated therewith are greater than the forces obtained via pneumatic means. A complication in such a type of device is that a comparatively large stroke length is required since the transporting means require a free passage in order to be able to place the lead frame on a machining station and then pick it up again. It is furthermore desirable to be able to visually inspect the machining zone.
The hydraulic driving also has other different drawbacks. Firstly, the use of a hydraulic medium is not easily compatible with the clean environment in which the process must take place. In addition, the accuracy of the movement via hydraulic means is limited, since this movement is only guided by one guide, the hydraulic piston rod. In the past different steps have been taken to increase this accuracy, but the possibilities are limited. Should it be desired to further increase the speed, the hydraulic drive imposes limits, since the speed is limited among other reasons because the driving hydraulic medium has to surmount a dead point during a complete cycle of the active stroke. The result is that the transport of the lead frame can only be performed when it has been established that the stroke of the tool has ended at a predetermined position.